Question

For two resistors R1 and R2 connected in a parallel , find the relative error in their equivalent resistance , if R1 = (50+- 2) ohm and R2 = (100+- 30 ) ohm

Answer 1

ɧɩ ʆɾɩҽŋɖ

Rp = 100 ×50 / 100+50
Rp = 500/15
Rp = 33.3

∆Rp / Rp^2 = ∆R1/ R1² + ∆R2 / R2²

∆R = ∆R1 ∆Rp ^2/ R1 ² + ∆R2 ∆Rp^2 / R2 ^²

=( 100x100 x 2 / 3 x 3 x 50 x 50 ) + ( 100 x 100 x 30 / 3 x 3 x 100 x 100 )

= 8/9 + 30 /9

= 38 /9

=± 4. 2

=( 33.33 ± 4.2 ) ohm

Answer 2

Req=1/R1+1/R2
1/50+1/100=33.33OHM
NOW DONT  SEE SYMBOL,I M GOING TO WRITE FULL NAMES
WE KNOW FORMULA
delta R eq/R SQUARE eq=delta R1/R1 SQUARE + delta R2 /R2 SQUARE
>delta R eq /R eq+[delta R1/R1 SQUARE + delta R2 /R2 SQUARE]R eq
(2/square of 50 + 3/ square of 100)33.33
1/1250+3/10000 ,
(.0008+.0003)33.33
.036 Answer.